A vacuum robot is conventionally known for handling substrates in vacuum (Patent reference 1, for example). A vacuum robot disclosed in Patent reference 1 is equipped with a hand on which a substrate is mounted, an arm to which the hand is linked to the front end thereof, and a main body unit to which the base end of the arm is linked The arm is configured by an arm base which is rotatably linked to the main body unit, a first arm which is rotatably linked to the arm base with the base end thereof and a second arm which is rotatably linked to the front end of the first arm with the base end thereof. The arm base and the first arm are formed hollow. Arranged inside the arm base are an arm-driving motor which drives the arm and a first reduction gear which reduces the rotation of the arm-driving motor and transmits it to the first arm. The base end of the first arm is fixed to the output shaft of the first reduction gear. A second reduction gear for reducing the rotation of the arm-driving motor and transmitting it to the second arm is arranged on the front end side of the first arm. The base end of the second arm is fixed to the output shaft of the second reduction gear.
In the vacuum robot disclosed in Patent reference 1, part of the main body unit is fixed to the bottom surface of a vacuum vessel, and the arm and the hand are arranged in vacuum. The interior space of the hollow arm base and the first arm is kept airtight atmospheric pressure. Therefore, even if the arm of this vacuum robot is placed in vacuum, there is no need to use an expensive lubricant such as vacuum grease for the first reduction gear and the second reduction gear, but a lubricant such as grease used at atmospheric pressure may be used. Consequently, the initial cost and the running cost of the vacuum robot can be reduced. Also, in the vacuum robot, even if the arm is arranged in vacuum, the arm-driving motor, which is arranged inside the arm base, can be cooled because the interior space of the arm base and the first arm is at atmospheric pressure.
Next, conventionally known is an original position returning method for returning an industrial robot, which performs a series of operations through a control program, to the original position from the position of an emergency stop (Patent reference 2, for example). In the original position returning method disclosed in Patent reference 2, an industrial robot is operated to perform predetermined operations to return to the original position, based on the coordinates of the current position of the industrial robot at the time of the emergency stop (the current status) recorded in a robot controller and the coordinates of the actual current position of the robot at the time of the emergency stop acquired based on the detection result by an encoder.
Also conventionally known is an articulated industrial robot which has an arm configured by multiple arm units (Patent reference 3, for example). The industrial robot disclosed in Patent reference 3 is equipped with an arm configured by a first arm unit which is rotatably linked to a main body unit, a second arm unit which is rotatably linked to the first arm unit and a third arm unit which is rotatably linked to the third arm unit, and two hands which are rotatably linked to the third arm unit. This industrial robot is also equipped with a first driving motor for driving the first arm unit and the second arm unit, a second driving motor for driving the third arm unit, and two driving motors for respectively driving the two hands. This industrial robot is placed at the entrance of a semiconductor manufacturing system, and takes semiconductors out of a cassette in which the wafers are stored and stores them in a predetermined processor.
Further, conventionally known is a semiconductor-handling robot which handles semiconductor wafers (Patent reference 4, for example). The handling robot disclosed in Patent reference 4 is a horizontal articulated tri-axial robot equipped with an elevating shaft which is provided to a base, an arm which is rotatably linked to the elevating shaft with the base end thereof, and a hand which is rotatably linked to the front end of the arm. The arm is configured by a first arm unit which is rotatably linked to the elevating shaft with the base end thereof and a second arm unit which is rotatably linked to the front end of the first arm unit with the base end thereof and to which the hand is rotatably linked to the front end thereof. Also, this handling robot is equipped with three motors for respectively driving the first arm unit, the second arm unit and the hand.
In the handling robot disclosed in Patent reference 4, the position of the hand is controlled based on the cylindrical coordinate system that uses the center of rotation of the first arm unit with respect to the elevating shaft as the original point. Also, disclosed in Patent reference 1 is an auto-teaching method to automatically teach the moving position of the hand to extend/fold in the arm so that the hand moves in a straight line on the line passing the center of rotation of the first arm unit when viewed in the top-bottom direction (that is, the hand moves in the radial direction of the cylindrical coordinate system). Note that there is a disclosure in Patent reference 4 that the position of the hand may be controlled based on the XY coordinate system.
The handling robot disclosed in Patent reference 4 is used in a semiconductor manufacturing system to manufacture semiconductors. In a semiconductor manufacturing system, conventionally, a semiconductor wafer processor is arranged radially having the center of rotation of the first arm unit as a center when viewed in the top-bottom direction; the handling robot moves the hand radially having the center of rotation of the first arm unit as a center (that is, the robot moves the hand on the straight line passing the center of rotation of the first arm unit) to handle a semiconductor wafer.